1. Field of the Invention
The present invention generally relates to implements for use in agriculture and more particularly to implements for planting seed crops.
2. Background of the Invention and Description of the Prior Art
Motorized or mobile implements for planting seed are known in the prior art. One example is the “Vacumeter” planter implement manufactured by Deere & Company under the John Deere brand name. Each unit is a single chassis that includes devices for surface preparation, discs for forming a furrow, a seed dispenser for depositing the seeds into the furrow, closing wheels to close the furrow over the seeds, and a press wheel for “firming” the soil into the furrow so that the seeds are in close contact with the soil. The chassis, which is equipped with wheels, is typically towed by a tractor to provide preparation of the furrow, planting the seeds, and closing the furrow all by a single machine. Multiple planter units of this type may be ganged together to plant seed in multiple parallel rows. A disadvantage of this type of planter is that it offers no provision for planting the seed in soil having a specified moisture content that is favorable for seed germination.
U.S. Pat. No. 5,524,560 issued to Carter describes a “System for Controlling Vertical Displacement of Agricultural Implements into the Soil.” The system operates to “maintain the depth of a planter (or tiller) at a soil depth of optimal moisture content” in response to the output of a soil resistivity sensor. The system eschews the use of planter structures as electrodes, but includes other structural features said to improve the accuracy of the soil resistivity measurement. It is limited to using the soil resistivity measurement to control the vertical displacement of the tiller implement corresponding to the moisture content indicated by the resistivity measurement. A disadvantage of this system is that it lacks the ability to control the moisture content of the soil used to cover the seed deposited into a furrow. Further, the system of Carter seeks a moisture level regardless of the depth it must go to reach soil having a suitable moisture content. Thus, the depth into which the seed is deposited may be the wrong depth for that type of seed.
In U.S. Pat. No. 5,841,282 issued to Christy et al., a “Device for Measuring Soil Conductivity” is disclosed that develops a soil conductivity measurement from voltage and current measurements taken by first and second pairs of coulters used as electrodes. The system is adapted to provide data on topsoil texture and depth, and also soil conductivity at two or more soil depths. The system is used to gather and map accurate data about soil properties but does not apply the measurements directly during its operation to optimize planting in response to parameters such as soil moisture content.
U.S. Pat. No. 8,204,689, also issued to Christy et al., for a “Mobile Soil Mapping System for Collecting Reflectance Measurements” describes optical apparatus for collecting spectroscopic measurements of soil properties in a field, specifically to determine soil carbon levels and other related properties. Again, the disclosed system is a data gathering and mapping system that is not adapted to directly using such data to control the planting of seeds in a field.
In the planting of particular types of seed it is desired to plant the seed so that it is placed in soil having the optimum moisture content for germination. Planting the seeds at some depth corresponding to a desired moisture content is only an approximation, and may not be a desirable depth for other reasons. Different types of seed thrive during the germination phase at differing depths and differing moisture content, often depending on the particular variety of seeds and the type of soil. It would be preferred that seeds could be planted at their recommended depth for the seed variety under local conditions and be provided soil at that depth that had the preferred moisture content. The foregoing systems are unable to accomplish this in real time during the planting operation.